T
here have been few studies on the combined effects of acid-base balance and vitamin D status on muscle mass and metabolism. Consequently, researchers set out to investigate whether alkali supplementation with potassium bicarbonate (KHCO3), with or without vitamin D3 (±VD3), alters urinary nitrogen (an indicator of muscle proteolysis) and other indicators affecting signaling pathways that regulate muscle mass.

Thirty-six rats were randomly assigned to one of two KHCO3-supplemented diets (±VD3) or diets without KHCO3 (±VD3) for 12 weeks. Thereafter, several different groups of muscles were examined.

Among VD3-dosed rats, phosphorylated-Akt protein expression was twofold higher in the KHCO3 groups compared to those who were not given KHCO3, but this effect was blunted in rats on VD3-deficient diets. Furthermore, in rats experiencing metabolic acidosis, higher vitamin D status seemed to work synergistically with KHCO3 to potentiate Akt activation, a protein kinase involved in several anabolic pathways.

These findings provide support for alkali supplementation (certainly as KHCO3) as a promising intervention to promote preservation of skeletal muscle mass, particularly along with higher vitamin D.